New 3D printing method enables precise multi-material objects

Researchers at MIT and TU Delft have developed an innovative 3D printing technique that produces objects with different colours, shades and textures in a single operation. The method, known as ‘speed-modulated ironing’, uses heat-sensitive materials and a dual-nozzle printer.

The process works with two nozzles: the first nozzle applies the heat-sensitive filament, while the second nozzle activates it by applying heat. By controlling the speed of the second nozzle, the colour, shading and roughness of the material can be precisely adjusted.

Mustafa Doğa Doğan, co-author of the study, explains: ‘We want to achieve a greater variety of properties for 3D-printed objects with a limited set of materials.’ The team developed a model that predicts the heat transfer of the ‘ironing’ nozzle based on its speed.

The researchers integrated this model into a user interface that automatically generates printing instructions for desired colour, shading and texture specifications. The system requires no hardware modifications, making it particularly practical.

In tests, the scientists used three heat-sensitive filaments: a foaming polymer for different shades and textures, and wood and cork fibre-filled filaments for darker tones. They demonstrated the versatility of the method using partially transparent water bottles and bicycle handles with variable roughness.

Compared to conventional multi-material 3D printing processes, the new technology proved to be faster, more material-efficient and more energy-efficient. It also enables finer gradations in shades and textures.

The researchers are planning to extend the method to other thermally reactive materials such as plastics. Modifying the mechanical and acoustic properties of certain materials is also on their agenda.

This development could significantly increase the flexibility and efficiency of 3D printing. It opens up new possibilities for the production of complex, multifunctional objects in a single operation. Applications range from artistic effects to ergonomically optimised products. The research results will be presented at the ACM Symposium on User Interface Software and Technology.